242 THE HAEMOFLAGELLATES 



anterior end ; the flagellum is not attached to the side of the body at 

 all but straightway becomes free, and there is no sign of an undulat- 

 ing membrane. These forms are mostly parasitic in Invertebrates 

 which do not suck blood. In //. subttlaift, however, which is parasitic 

 in the digestive-tube of Tabanus and Haematopota, predatory on cattle 

 and horses, the kinetonucleus lies much farther from the anterior 

 end, and may be almost opposite the trophonucleus (Fig. 29, F). 

 The flagellum, which has been, as it were, drawn back with it, is in 

 most individuals attached for the proximal part of its length to the 

 anterior part of the body, by means of a delicate cytoplasmic 

 border, which constitutes a rudimentary undulating membrane. 

 Thus there is an approach to a trypaniform condition. Again, in 

 the case of Crithidia fasciculata, found in the intestine of mosquitoes, 

 Leger has described a very distinct undulating membrane, which 

 gives the parasite, especially in the more elongated individuals, a 

 very Trypanosome-like appearance. Novy and his colleagues have 

 also studied C. fasciculata, as found in Culex ; but while admitting 

 the presence of a membrane, regard it as imperfect and only 

 poorly developed. These authors describe, in addition, another 

 Herpetomonadine type, H. (Trypanosoma) culicis, the long forms of 

 which show clearly an undulating membrane. 



We are now in a position to discuss the relation (if any) of 

 these Flagellates to the Trypanosomes of Vertebrates. When 

 first describing Crithidia, L6ger expressed the opinion that this 

 parasite was very likely only a stage in the development of a 

 Haemoflagellate ; further, in his notes on H. subulata (52) he 

 added the remark that the same was probably true of many of these 

 Herpetomonad or Crithidial forms found in biting Insects, though 

 this would not apply, of course, to those species occurring in non- 

 biting Insects (such as Musca, Sarcophaga, etc.). Moreover, Schaudinn 

 himself (I.e.) comments on the great similarity between (what he 

 took to be) the phases of Trypanomorpha noctuae in Culex and those of 

 Lexer's Crithidia. 



Quite the opposite view is held by Novy and M'Neal, who, 

 after first (62) regarding the Flagellates found by Schaudinn in 

 mosquitoes as being simply " cultural " forms, of no real significance 

 in the life-history, in their later paper (63) consider it much more 

 likely that the Insectan parasites are entirely distinct from the 

 Trypanosomes in the blood. (They look upon the parasites found 

 in leeches, however, as "cultural" forms of Piscine Trypanosomes.) 

 A similar opinion is expressed by Ross, who points out that he 

 found Crithidia in the mosquitoes (larvae and pupae) before they 

 fed on blood, and thinks the parasites were in the first place 

 swallowed by the larvae. 



In a very interesting note Patton has recently (65) described 



